gen/FreeBSD/getcwd.c

   1 /*
   2  * Copyright (c) 1989, 1991, 1993, 1995
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  29
  30 #if defined(LIBC_SCCS) && !defined(lint)
  31 static char sccsid[] = "@(#)getcwd.c    8.5 (Berkeley) 2/7/95";
  32 #endif /* LIBC_SCCS and not lint */
  33 #include <sys/cdefs.h>
  34 __FBSDID("$FreeBSD: src/lib/libc/gen/getcwd.c,v 1.29 2007/01/09 00:27:53 imp Exp $");
  35
  36 #include "namespace.h"
  37 #include <sys/param.h>
  38 #include <sys/stat.h>
  39
  40 #include <dirent.h>
  41 #include <errno.h>
  42 #include <fcntl.h>
  43 #include <stdio.h>
  44 #include <stdlib.h>
  45 #include <string.h>
  46 #include <unistd.h>
  47 #include "un-namespace.h"
  48
  49 #define ISDOT(dp) \
  50         (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
  51             (dp->d_name[1] == '.' && dp->d_name[2] == '\0')))
  52
  53 extern int __getcwd(char *, size_t);
  54
  55 char *
  56 getcwd(pt, size)
  57         char *pt;
  58         size_t size;
  59 {
  60         struct dirent *dp;
  61         DIR *dir = NULL;
  62         dev_t dev;
  63         ino_t ino;
  64         int first;
  65         char *bpt, *bup;
  66         struct stat s;
  67         dev_t root_dev;
  68         ino_t root_ino;
  69         size_t ptsize, upsize;
  70         int save_errno;
  71         char *ept, *eup, *up, c;
  72
  73         /*
  74          * If no buffer specified by the user, allocate one as necessary.
  75          * If a buffer is specified, the size has to be non-zero.  The path
  76          * is built from the end of the buffer backwards.
  77          */
  78         if (pt) {
  79                 ptsize = 0;
  80                 if (!size) {
  81                         errno = EINVAL;
  82                         return (NULL);
  83                 }
  84                 if (size == 1) {
  85                         errno = ERANGE;
  86                         return (NULL);
  87                 }
  88                 ept = pt + size;
  89         } else {
  90                 if ((pt = malloc(ptsize = PATH_MAX)) == NULL)
  91                         return (NULL);
  92                 ept = pt + ptsize;
  93         }
  94         if (__getcwd(pt, ept - pt) == 0) {
  95                 if (*pt != '/') {
  96                         bpt = pt;
  97                         ept = pt + strlen(pt) - 1;
  98                         while (bpt < ept) {
  99                                 c = *bpt;
 100                                 *bpt++ = *ept;
 101                                 *ept-- = c;
 102                         }
 103                 }
 104                 return (pt);
 105         }
 106         bpt = ept - 1;
 107         *bpt = '\0';
 108
 109         /*
 110          * Allocate 1024 bytes for the string of "../"'s.
 111          * Should always be enough.  If it's not, allocate
 112          * as necessary.  Special case the first stat, it's ".", not "..".
 113          */
 114         if ((up = malloc(upsize = 1024)) == NULL)
 115                 goto err;
 116         eup = up + upsize;
 117         bup = up;
 118         up[0] = '.';
 119         up[1] = '\0';
 120
 121         /* Save root values, so know when to stop. */
 122         if (stat("/", &s))
 123                 goto err;
 124         root_dev = s.st_dev;
 125         root_ino = s.st_ino;
 126
 127         errno = 0;                      /* XXX readdir has no error return. */
 128
 129         for (first = 1;; first = 0) {
 130                 /* Stat the current level. */
 131                 if (lstat(up, &s))
 132                         goto err;
 133
 134                 /* Save current node values. */
 135                 ino = s.st_ino;
 136                 dev = s.st_dev;
 137
 138                 /* Check for reaching root. */
 139                 if (root_dev == dev && root_ino == ino) {
 140                         *--bpt = '/';
 141                         /*
 142                          * It's unclear that it's a requirement to copy the
 143                          * path to the beginning of the buffer, but it's always
 144                          * been that way and stuff would probably break.
 145                          */
 146                         bcopy(bpt, pt, ept - bpt);
 147                         free(up);
 148                         return (pt);
 149                 }
 150
 151                 /*
 152                  * Build pointer to the parent directory, allocating memory
 153                  * as necessary.  Max length is 3 for "../", the largest
 154                  * possible component name, plus a trailing NUL.
 155                  */
 156                 while (bup + 3  + MAXNAMLEN + 1 >= eup) {
 157                         if ((up = reallocf(up, upsize *= 2)) == NULL)
 158                                 goto err;
 159                         bup = up;
 160                         eup = up + upsize;
 161                 }
 162                 *bup++ = '.';
 163                 *bup++ = '.';
 164                 *bup = '\0';
 165
 166                 /* Open and stat parent directory. */
 167                 if (!(dir = opendir(up)) || _fstat(dirfd(dir), &s))
 168                         goto err;
 169
 170                 /* Add trailing slash for next directory. */
 171                 *bup++ = '/';
 172                 *bup = '\0';
 173
 174                 /*
 175                  * If it's a mount point, have to stat each element because
 176                  * the inode number in the directory is for the entry in the
 177                  * parent directory, not the inode number of the mounted file.
 178                  */
 179                 save_errno = 0;
 180                 if (s.st_dev == dev) {
 181                         for (;;) {
 182                                 if (!(dp = readdir(dir)))
 183                                         goto notfound;
 184                                 if (dp->d_fileno == ino)
 185                                         break;
 186                         }
 187                 } else
 188                         for (;;) {
 189                                 if (!(dp = readdir(dir)))
 190                                         goto notfound;
 191                                 if (ISDOT(dp))
 192                                         continue;
 193                                 bcopy(dp->d_name, bup, dp->d_namlen + 1);
 194
 195                                 /* Save the first error for later. */
 196                                 if (lstat(up, &s)) {
 197                                         if (!save_errno)
 198                                                 save_errno = errno;
 199                                         errno = 0;
 200                                         continue;
 201                                 }
 202                                 if (s.st_dev == dev && s.st_ino == ino)
 203                                         break;
 204                         }
 205
 206                 /*
 207                  * Check for length of the current name, preceding slash,
 208                  * leading slash.
 209                  */
 210                 while (bpt - pt < dp->d_namlen + (first ? 1 : 2)) {
 211                         size_t len, off;
 212
 213                         if (!ptsize) {
 214                                 errno = ERANGE;
 215                                 goto err;
 216                         }
 217                         off = bpt - pt;
 218                         len = ept - bpt;
 219                         if ((pt = reallocf(pt, ptsize *= 2)) == NULL)
 220                                 goto err;
 221                         bpt = pt + off;
 222                         ept = pt + ptsize;
 223                         bcopy(bpt, ept - len, len);
 224                         bpt = ept - len;
 225                 }
 226                 if (!first)
 227                         *--bpt = '/';
 228                 bpt -= dp->d_namlen;
 229                 bcopy(dp->d_name, bpt, dp->d_namlen);
 230                 (void) closedir(dir);
 231                 dir = NULL;
 232
 233                 /* Truncate any file name. */
 234                 *bup = '\0';
 235         }
 236
 237 notfound:
 238         /*
 239          * If readdir set errno, use it, not any saved error; otherwise,
 240          * didn't find the current directory in its parent directory, set
 241          * errno to ENOENT.
 242          */
 243         if (!errno)
 244                 errno = save_errno ? save_errno : ENOENT;
 245         /* FALLTHROUGH */
 246 err:
 247         save_errno = errno;
 248
 249         if (ptsize)
 250                 free(pt);
 251         if (dir)
 252                 (void) closedir(dir);
 253         free(up);
 254
 255         errno = save_errno;
 256         return (NULL);
 257 }